When thin sheet-like substrates, such as glass plates or wafers, are conveyed to each processing stage, a cassette containing these substrates, which are stacked in layers, is used. This cassette is lowered by a transfer apparatus onto a supporting board disposed at a substrate-taking-out position of each processing stage. The substrates contained in the cassette are then taken out by a substrate-taking-out robot provided beside the supporting board, and are supplied to a processing position. The substrate-taking-out robot is automatically controlled, and hence, in order to allow the robot to reliably and smoothly take the substrates out of the cassette without exerting an excessive force on the substrates, the accuracy of the posture or position of the cassette transferred onto the supporting board disposed at the substrate-taking-out position must be made sufficiently high. Therefore, a cassette-deviation automatic correction apparatus used to automatically correct positional deviations in horizontal two-dimensional directions of the cassette vertically lowered by the transfer apparatus is provided on the supporting board at the substrate-taking-out position to which the cassette is transferred. Examples of conventional load-positioning apparatuses that can be used for such a cassette-deviation automatic correction apparatus include an apparatus that needs a driving source and that is of a type that pushes a load, which has been lowered on the supporting board while being kept in a positionally deviated state, toward a fixed position by use of a pusher driven by a driving means and an apparatus that does not need a driving source and that is of a type that drives a pusher (roller) that pushes a load toward a fixed position by use of the weight of the load vertically lowered by a transfer apparatus as disclosed by Japanese Published Unexamined Utility Model Application No. H5-37755.
A plurality of load positioning apparatuses that differ from each other in a deviation correcting direction must be disposed around the supporting board to which the cassette is lowered by the transfer apparatus. Therefore, if the cassette-deviation automatic correction apparatus is composed of the load positioning apparatuses of the type that needs a driving source, a pusher driven by a driving means is required for each of the load positioning apparatuses disposed at a plurality of positions around the supporting board to which the cassette is lowered by the transfer apparatus. Since a control device is additionally required for the driving means, an extremely high equipment cost must be paid for the entire cassette-deviation automatic correction apparatus, and there is a high possibility that control system trouble will cause a breakdown. On the other hand, if the cassette-deviation automatic correction apparatus is composed of the load positioning apparatuses of the type that does not need a driving source, it will be possible to resolve the problem occurring when the load positioning apparatuses of the type that needs a driving source are used. However, the motion of, for example, an up-and-down movable lever depressed by a cassette lowered vertically while being supported by the transfer apparatus is converted into a pushing motion of the pusher (roller) pushing the descending cassette toward the fixed position, and hence the cassette descending while being supported by the transfer apparatus is horizontally moved on a supporting surface of the transfer apparatus. However, in recently-used facilities that handle a large-sized, enormously-heavy (about 1000 Kg) cassette that contains large-sized glass plates, the heavy cassette cannot be horizontally and smoothly moved on the supporting surface of the transfer apparatus, and hence such facilities cannot employ the load positioning apparatus structured as above.